630 THE INTERNAL SECRETIONS AND IMMUNITY. 



depicted a few pages back becomes enhanced. The epithelial 

 cells of the pulmonary alveoli not only seize the pathogenic 

 germ, but they are capable of further insuring their destructive 

 work by first weakening their enemy with their secretion. If 

 bacteria penetrate the first line of defense, they meet not only 

 the free leucocytes beyond, but their alexins. It is when, if 

 still active, they become engaged in the capillary net-work, 

 however, that bacteria undergo their greatest exposure. In- 

 deed, both the fixed and wandering leucocytes and their secre- 

 tions are all crowded together in these vessels, or bactericidal 

 channels, and the pathogenic organisms, dragged along by the 

 blood-stream, must indeed be numerous to overcome the de- 

 fensive hosts placed across their path. 



If the toxic products of the bacteria in the blood exceed 

 a given limit, adrenal overactivity is awakened. An influx 

 of blood in the entire capillary system ensues, bringing along 

 with it a steadily increasing array of phagocytes, each endowed 

 with its poisonous atmosphere and capable of ingulfing a large 

 number of bacteria. Veins and venules, arteries and arterioles, 

 by responding through the muscular fibers in their walls to the 

 suprarenal impetus, lock up, as it were, the offensive and de- 

 fensive host together on the field of action, i.e., the capillaries, 

 the fluids in the connective tissue, lymph-spaces, etc., and, 

 "muscular vessels and capillaries being antagonistic in con- 

 traction and dilation," the latter are dilated through the 

 greater quantity of blood forced into them, and the efficiency 

 of the defensive processes is rendered all the more efficacious. 

 The heart-beats are slower, but firmer and stronger; the sur- 

 face of the body, replete with capillaries, is flushed and hot, 

 the temperature rises, etc. Briefly, all the signs of adrenal 

 overactivity, i.e., fever, appear, and continue until the patho- 

 genic organisms present are overcome. 



All diseases would end favorably in a previously healthy 

 subject were bacteria alone to be contended with. But the time 

 has long passed since micro-organisms were considered as the 

 pathogenic factors per se in the diseases in which they are 

 found. Precisely as leucocytes secrete or produce alexins, so 

 do bacteria produce toxins. In fact, as is well known, bacteria 

 need not enter the general circulation at all and still produce 



